Holding device for wheeled vehicles



Jan. 26, 1960 H. 1. CLARK, JR

HOLDING DEVICE FOR WHEELED VEHICLES Filed May 14, 1956 4 Sheets-Shea; 1

Jan. 26, 1960 H. l. CLARK, JR 2,922,494

HOLDING DEVICE FOR WHEELED VEHICLES Filed May 14, 1956 4 Sheets-Sheet 2 Jan. 26, 1960 H. l. CLARK, JR

HOLDING DEVICE FOR WHEELED VEHICLES Filed May 14, 1956 4 Sheets-Sheet 3 NVl-Z MT o L fli? 4 ado-4 I ca T-romsv" Jan. 26, 1960 H. 1. CLARK, JR 2;922,494

HOLDING DEVICE FOR WHEELED VEHICLES Filed May 14, 1956 4 Sheets-Sheet 4 HOLDING DEVICE FUR WHEELED VEHICLES Harry I. mark, in, Rockford, llh, assignor to Harry I. Clark Application May 14-, 1156, Serial No. 584,520

'5 Claims. ((31. 1885) This invention relates to a holding device for Wheeled vehicles of the type commonly used to support machine tools and the like so that the tools are portable and may be moved from place to place for use. After the vehicle has been moved to bring the tool into the proper position, it is necessary to hold the vehicle against 'movement during the machining operation.

In order to prevent such movement, the vehicle usually is provided with a holding device or lock which is carriedon the underside of the vehicle and has a foot which has a friction face and may be lowered to bring this face into engagement with the how or any other surface supporting the vehicle.

The general object of the invention is to provide a new and improved holding device of the above character which permits a large range of movement of the foot to provide maximum clearance when the foot is retracted, which is rendered effective to lock the vehicle by :the simple-depression of a manual member, which is arranged to retract the foot automatically simply by unlocking the manual member and which grips the floor with the same pressure regardless of the-amount the foot must be lowered to engage the filoor.

Amore detailed object is to form the holding device with two telescoping tubes or sleeves with one sleeve fixed to the vehicle and the other carrying the foot and to employ a manual member which first slides the second sleevedown and subsequently compresses a spring for holding the foot against the floor.

Another object is to lock the manual member initially so that it moves the foot down when it is depressed and then to release the member when the foot engages the floor so that the member is effective to compress the spring.

A further obiect is to provide a novel arrangement of the spring so that it moves bodily down with'the foot and thereafter is compressed whereby the amount the spring-is compressed always is the same regardless of the distance the :foot has been moved to engage the floor.

The invention also resides in the novel construction and arrangement of the manual member'and "in the .manner of operativelyconnecting the spring to various parts so that his effective to press the foot against the floor.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which .Figure l is a side elevation of a truck equipped with a holding device which embodies the novel features of the present invention.

Fig. -2 is a sectional view taken "along the line 22 in Fig. 1.

3 is an enlarged side view of the holding -device.

Fig. 4 is a fragmentary'secti'onal view on an enlarged scale taken along the line 4-4in Fig. 1 but shows the parts in a different position.

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2,922,494 Patented Jan. 26, 1960 ice Fig. 5 is a sectional view taken along the line 5-5 in Fig. 3.

Fig. 6 is an enlarged fragmentary sectional view of the lower portion of the holding device.

Fig. 7 is a view similar to Fig. 6 but shows the parts in a different position.

Fig. 8 is a fragmentary side view of the lower portion of the holding device, parts being broken away and shown in section.

Fig. 9 is an exploded perspective view of the parts used to connect the spring to the truck.

Fig. 10 is a fragmentary sectional view of the central portion of the holding device.

Fig. 11 is a front view of the holding device.

Fig. 12 is an exploded perspective view of the lower end portion of the holding device.

As shown in the drawings for purposes of illustration, the invention may be used in connection with a conventional truck 15 which comprises a horizontal platform 16 and a plurality of supporting wheels 17. In building aircraft and similarly large pieces of equipment, it is common to support large tools and like apparatus on a truck of this character so that the tool is portable and may be moved from place to place to effect machining operations on different parts of the aircraft.

During the machining operation, it is essential to hold the truck in a stationary position. This is achieved by utilizing one or more holding devices 18 which are mounted on the underside of the platform 16. In this instance, there are two such devices, one at each side of the platform, and each includes a foot 19 which is formed with a friction face 26) (Fig. 3). The latter faces downwardly and the foot may be lowered to bring the friction face into engagement with the floor 21 or other Surface supporting the wheels 17. The friction between the face and the floor prevents the truck from moving.

The Present invention contemplates the provision of a' novel holding device 18 which permits a long range of vertical movement of the foot 19 so as to provide maxi mum clearance when the foot is retracted and which also grips the floor 21 with the same pressure regardless of the distance the foot is required to move to bring the friction face '20 into engagement with the floor. Also, according to the invention, the holding device is operated by a manual member '22 which is effective upon the application of a simple downward pressure first to lower the foot and then 'to lock the foot in the lowered position. The parts are also arranged in a novel manner so that the foot is retracted automatically simply by unlocking the manual member.

In general, the holding device comprises an outer'tube or sleeve 23 and an inner sleeve 24 telescoped Within the outer sleeve and carrying the foot 1?. The upper end of the outer sleeve is welded'to a plate 25 which, in turn, is bolted to-the underside of the platform 16.

The foot 19 includes a gripping pad 236 which is made of any suitable friction material such as rubber. The lower surface of the pad constitutes the friction face'Zi) and the pad is "secured to the underside of a backing plate 27'. Pins 28 upstanding from the backing plate project loosely through holes 29 (see Fig. 12) in a secend plate "34) which is welded to the lower end of the inner tube 24. The pins are formed with heads which prevent the pins from dropping throug'hthe holes 29 and the loose fitb'etwe'en the pins and the holes pcrmitsathe foot "to moverelative tothe inner tube 'sothat it may be angularly disposed to'co-mpensatefor irregularities in-the surface of-the floor 21 as shown in-F-ig. 4.

Relative turning-between the outerand inner tubes 23 and 24 is prevented by-two links 31 and.32. The two links are pivoted together at adjacent ends as indicated at as. The other end of the link 31 is bifurcated and is attached to ears 34 on the outer tube while the other link 32 similarly is bifurcated and is pivotally connected to cars 35 upstanding from one side of the plate 38. Thus, the links prevent the tubes from turning while permitting the inner tube to slide into and out of the outertube'.

Normally, the foot 19 is held up in the retracted position by a circular spring 35 (Figs. 4, 6 and 7) which is disposed within a vertical tube 37. The latter is coaxial with the outer tube 23 and depends rigidly from the top plate 25. The upper end of the spring is hooked over a pin 38 extending across the upper end of the tube and the lower end of the spring is connected to an inverted U-shaped wire 39. The ends of the wire are hooked respectively to two pawls 40 which are pivotally supported by a horizontal pin 41. The latter is rigid with the plate 3!} spanning a central hole 42 in the plate, and is mounted on the latter by means of a ring 43 which encircles the hole (see Fig. 12). The ring is welded to the plate 30 and clamps the pin against this plate. Since the plate 30 is a part of the foot 19, the spring 36, acting through the wire 39 and the pawls 40, lifts the foot and hence the inner sleeve 24.

For a purpose to be described later, the pawls '40 constitute a latch connecting a third sleeve 44 to the foot 19- The sleeve 44 slides inside the inner sleeve 24 and normally is disposed near the lower end thereof. The spring 36 tends to turn the pawls 40 about their pivot pin 41 toward each other so that the pawls hook around a horizontal bar 45 which is rigid with and extends diametrically across the lower portion of the sleeve 44.

In this position (Fig. 6), the pawls lock the bar and hence the sleeve 44 to. the plate 30 of the foot. When the pawls swing apart as shown in Fig. 7, they release the sleeve so that the latter may slide independently of the foot.

In order to lower the foot 19 and bring the friction face 20 against the floor 21, the manual member 22 is mounted on the foot to move relative to the latter between a first position shown in Fig. 3 and a second position shown in full lines in Fig. 8. The manual member "is held in the first position by the latch, that is, the

pawls 40, so that depressing the member lowers the foot 19 and the inner sleeve 24. The latch releases the memher in response to the foot engaging the floor and thereby permits the member to be moved to the second position. This is an over center position and, therefore, the spring 36 cannot raise the foot and the inner sleeve so that the holding device remains in the active condition.

Herein, the manual member 22 is a pedal pivotally mounted at one end on the bar 45. Also pivotally connected to the bar is a link 46 (Figs. 3 and 8) whose other end is pivotally joined to a lever 47 at 47a. The latter is fulcrumed on the plate 30 by a pin 48 which extends horizontally between ears 49 upstanding from the plate.

In the first or normal position of the pedal 22, a surface 50 (Figs. 3 and 8) abuts against the upper edge of the link 46. Also, the bar 45 projects into a vertical slot 52a (Figs. 4 and 7) so that the inner end of the pedal can move only up and down. In effect, therefore, these three elements, the pedal, the link and the lever constitute a single lever fulcrumed at 48. Because the pawls 40 hold the bar 45, however, the pedal, the link and the lever cannot turn about the fulcrum. As a result, pressing the pedal merely pushes down on the foot 19 and slides the inner tube 24 and the foot toward the floor.

The pawls 40 are released automatically as an incident to the foot 19 engaging the floor 21 to permit the pedal 22 at that time to be moved toward the second position. The release of the pawls is effected by taking advantage of the relative movement between the foot and the plate 30. To this end, the pawls are formed with extensions 51 (Fig. 6) which cross and project down through the hole 42 in the plate 30 and engage a boss 52 in the center portion of the plate 27. When the foot engages the floor, it stops but the inner sleeve 24 and hence the plate 30 continue to move down, this being permitted by the sliding of the pins 28 in the holes 29. As a result, the pawls move down relative to the plate 27. This relative movement spreads the pawl extensions and swings the pawls away from the bar as shown in Fig, 7 thereby releasing the pedal and permitting the lever 47 to swing about its fulcrum 48.

After the pawls 40 have released the bar 45, continued pressing on the pedal 22 causes the pedal, the link 46 and the lever 47 to turn about the fulcrum 48. Because the pivot of the pedal 22, that is, the bar 45, projects into the slot 52a, the inner end of the pedal is restrained so that it can only move upwardly. The combined eifects of the upward movement of the bar 45 and the counterclockwise rotation of the lever 47 (as viewed in Figs. 6 and 7) causes the bar 45 to move up and the pivot 47a to move across the line between the pivot 45 and the fulcrum 48 to the position shown in Fig. 8. In this position, the pivot 47a has moved over center and prevents the pedal, the link and the lever from returning to their original position. Because these parts, and hence the inner sleeve 24 and the foot 19 are locked in the down position as shown in Fig. 11, there is a link 46 and a lever 47 on each side of the sleeve 23 and these links and levers are connected through the medium of the bar 45 and the pedal 22 so that the two links and the two levers act in unison.

A torsion spring 53 is wound around the bar 45 and acts between one of the links 46 and the pedal 22. When the pedal is released after the pivot 47a has passed over center, the spring 53 raises the pedal to the position shown in broken lines in Fig. 8 without changing the positions of the links, the levers 47, the inner sleeve 24 and the foot 19. With the pedal in this raised position, a rod 54, which spans the two levers 47 is accessible from the side of the truck. By depressing the rod, the pivot 47a is moved back across center and, since the pivot has crossed center, the spring 36 again is free to raise the pawls 40 and hence the foot 19 since the pedal, the links and the levers are, at that time, capable of being returned to their original position.

A compression spring 55 encircling the tube 37 inside the inner sleeve 24 acts between the outer tube 23 and the foot 19 to press the foot against the floor 21. Advantage is taken of the movement of the pedal 22 from its initial position to the over center position to compress the spring 55 so that it exerts a downward force on the foot. For this purpose, the lower end of the spring abuts against the sleeve 44. Thus, as the pedal is moved from the first to the second position, the bar 45 slides up in the slot 52a. This raises the sleeve 44 and compresses the spring 55. When the sleeve is fully raised as shown in Figs. 8 and 10, the spring acts downwardly through the sleeve 44, the links 46 and the levers 47 on the foot 19 and presses the foot against the floor.

In order that the spring 55 is compressed the same amount and thereby exerts the same force regardless of the distance the foot 19 must travel to engage the floor, the spring moves bodily downwardly with the inner sleeve 24 and then, when the foot engages the floor, it is automatically connected with the outer sleeve 23. In this way, the spring always is in the same condition when the foot engages the floor and the same movement of the pedal 22 is effective to compress the spring whether the foot has moved a long distance or a short distance.

To achieve the foregoing, a washer 56 (Figs. 9 and 10) floats on top of the spring 55 and a projection 57 upstanding from the washer contacts the underside of a second washer 58 encircling the tube 37. The projection engages only one side of the washer 58. Thus, as the sleeve 44 is raised initially, it lifts the spring 55. This raises the washer 56 which, through the projection 57, tilts the Washer 58 as shown in Fig. thereby locking the washer 58 against the tube 37. Continued upward movement of the sleeve 44 compresses the spring 55 against the washer 56 which is held stationary by the Washer 58. In other Words, the washer 56 constitutes a movable upper abiitment for the spring and this abutment moves the same distance as the foot 19. When the washer 58 is tilted, it connects the washer 56 to the outer sleeve 23 through the tube 37 and the plate 25.

Operation With the arrangement described above, the truck is wheeled into the desired position and then the operator steps on the pedal 22 of each of the holding devices 18. At this time, the parts of the holding device are in the position shown in Fig. 6. Thus, the inner tube 24 is telescoped within the outer tube 23, the foot 19 is up, the pawls 4t) engage the bar 45 and the .pedal abuts against the link 46.

Because the bar '45 is held stationary relative to the foot 1?, the lever 47 cannot turn about its fulcrum and hence the pedal 22 can only move downwardly bodily with the foot and the inner tube 24. As a result, de pression of the pedal lowers the foot towards the floor 21.

When the pad 26 of the foot 19 contacts the floor, it stops but the plate 30 continues to move down a short distance, this being permitted by the pins 28 and holes 29. This relative movement between the plate and the foot swings the pawls 40 apart and releases the bar 45. At this time, therefore, the pedal 22, the link 46 and the lever 47 are free to turn about their respective pivots.

With the bar 45 released, continued depression of the pedal moves the latter clockwise as viewed in Fig. 6. The bar 45 rides up in the slot 52a and the lever 47 turns counterclockwise until the pivot 47a passes between the pivots 45 and 48. The linkage for the pedal, therefore, is in an over center position and this prevents the return spring 36 from raising the foot and the inner sleeve. When the pedal is released, the torsion spring 53 raises the pedal to the position shown in broken lines in Fig. 8 without changing the over center position of the link 46 and lever 4.7.

During the downward movement of the inner sleeve 24 and the foot 19, the sleeve 44 also was moved down since it was connected to the foot through the pawls 40 and the spring 55, which at that time was simply resting on the sleeve 44, moved down a corresponding amount. As the bar 45 moves up in the slot 52, it also lifts the sleeve 44 to which it is secured. This raises the spring which, in turn, lifts the washer 56 and thereby tilts the washer 58 and locks the latter to the tube 37. With the washer 58 locked, the washer 56 constitutes a fixed abutment for the spring which thereafter is compressed by the further upward movement of the sleeve 44. When the pedal 22 reaches the position shown in full lines in Fig. 8, the spring 55 is fully compressed as shown in Fig. 10.

At that time, the spring produces a downward force on the foot through the bar 45, the link 46 and the lever 47. This force presses the foot against the floor.

When it is desired to release the holding device, the operator pushes down on the rod 54. This turns the lever clockwise and moves the pivot 47:: back across center. As soon as this pivot crosses over center, the return spring 36 is free to lift the foot 19 and raise the inner tube 24 back up inside the outer tube 23. At the same time, this returns the pedal 22, the link 46 and the lever 47 to their original positions.

I claim as my invention:

1. A holding device for a wheeled vehicle comprising a first generally vertical tube adapted to be secured to the vehicle, a second tube telescoping with said first tube to slide relative to the latter toward and away from the surface supporting the vehicle, a foot carried on the lower end of said second tube and having a friction face en ageable with said surface, a manually operable membeimounted on said 'foot to move relative to said foot between fir's't and second positions, a latch means operable when engaged to connect 'said member to said second tube thereby to hold said member in said first position against movement relative to said foot whereby the foot and said second tube are lowered when said memher is depressed, means responsive to engagement of said face with said surface and operable upon such engagement to release said latch "and permit said member to move to said second position, a compression spring, mechanism operable to compress said spring upon movement of said member to said second position, and means connecting opposite ends of said spring to said first tube and said foot whereby the spring when compressed urges said fa'ce 'against 'said surface. v

2. A holding device for a wheeled vehicle comprising a first generally vertical tube adapted to be secured to the vehicle, 'a second tube telescoping with said first tube to slide relative to the latter toward and away from the surface supporting the vehicle, a foot disposed at the lower end of said second tube and having a friction face engageable with said surface, means supporting said foot on said second tube for vertical movement relative to the latter when said face engages said surface, a manually operable member mounted on said foot to move relative to said foot between first and second positions, a latch locking said member in said first position and holding the member against movement relative to said foot whereby the foot and said second tube are lowered when said member is depressed, means connecting said foot and said latch to release the latch upon movement of said foot relative to said second tube and permit said member to move to said second position, a compression spring, mechanism coupling said member to said spring to compress said spring upon movement of said member to said second position, and means connecting said spring when the latter is compressed to act between said first tube and said foot thereby to press said face against said surface.

3. A holding device for a wheeled vehicle comprising a first elongated vertical member adapted to be secured to said vehicle, a second elongated member telescoping with said first member, a foot carried on the lower end of said second member and having a friction face adapted to engage the surface supporting the vehicle, an over center linkage comprising a lever fulcrumed at one end on said foot and a link joined at one end to the other end of said lever by a first pivot, said lever and said link being disposed in vertical planes, a manually operable element joined to the other end of said link by a second pivot to move relative to said foot and swing said first pivot in between the second pivot and said fulcrum thereby to place said linkage in an over center position, a latch operable to lock said element to said foot whereby said second member, said foot and said linkage move down bodily together when said element is depressed, means responsive to engagement between said foot and said surface and operable upon such engagement to release said latch and permit said element to move said linkage into said over center position and hold the foot down against said surface, and a stop engageable by said linkage to hold the linkage in said over center position.

4. A holding device for a wheeled vehicle comprising a first elongated veritcal member adapted to be secured to said vehicle, a second elongated member telescoping with said first member, a foot carried on the lower end of said second member and having a friction face adapted to engage the surface supporting the vehicle, a manually actuated element connected to said foot and operable initially to lower said second member and said foot to move said face into engagement with said surface, a com pression spring having one end connected to said element to move up and down with said foot, a releasable connection between the other end of said spring and said rst member, said element being movable relative to rid foot after said face engages said surface, and means :sponsive to the relative movement between said eleient and said foot and operable to activate said connecon and compress said spring whereby the spring acts irough said element to press the foot against said surface. 5. A holding device for a wheeled vehicle comprising first elongated vertical member adapted to be secured said vehicle, a second elongated member telescoping 'ith said first member, a foot carried on the lower end f said second member and having a friction face adapted engage the surface supporting the vehicle, an over enter linkage comprising a lever fulcrumed at one end n said foot and a link joined at one end to the other ad of said lever by a first pivot, said lever and said link eing disposed in vertical planes, a manually operable lement joined to the other end of said link by a second ivot to move relative to said foot and swing said first ivot in between the second pivot and said fulcrum thereby place said linkage in an over center position, a latch operable to lock said element to said foot whereby said second member, said foot and said linkage move down bodily together when said element is depressed, means responsive to engagement between said foot and said surface and operable upon such engagement to release said latch and permit said element to move said linkage into said over center position and hold the foot down against said surface, a stop engageable by said linkage to hold the linkage in said over center position, a compression spring, and means responsive to the movement of said element after said foot engages said surface and operable first to connect said spring to said member and said second pivot and then to compress the spring whereby the spring holds the foot against the surface.

Anderson Mar. 25, 1941 Herold Oct. 24, 1944 

